COMPACT AND COST-EFFECTIVE MOBILE 2.4 GHZ RADAR SYSTEM FOR OBJECT DETECTION AND TRACKING

Various types of small mobile objects such as recreational unmanned vehicles
have become easily approachable devices to the public because of technology
advancements. The technology advancements make it possible to manufacture
small, light, and easy to control unmanned vehicles, therefore the public are able to
handily access those unmanned vehicles. As the accessibility to unmanned vehicles
for recreational purposes, accidents or attacks to threat a person using those the
unmanned vehicles have been arising and growing rapidly. A specific person could
be a target of a threat using an unmanned vehicle in open public places due to its
small volume and mobility. Even though an unmanned vehicle approaches to a
person, it could be difficult to detect the unmanned vehicle before the person
encounters because of the compact size and maneuverability.

This research is to develop a radar system that is able to operate in open
public areas to detect and track unmanned vehicles. It is not capable using existing
radar systems such as for navigation, aviation, national defense, air traffic control,
or weather forecasting to monitor and scan public places because of large volume,
high operation cost, and danger to human health of the radar systems. For example,
if electromagnetic fields emitted from high-power radar penetrate exposed skin
surface or eyes, the energy from the electromagnetic fields can cause skin burns, eye
cataracts, or more (Zamanian & Hardiman, 2005). Therefore, a radar system that
can perform at the public place is necessary for monitoring and surveillance the area.

The hardware of this proposed radar system is composed of three parts: 1)
radio frequency transmission and receiver part which we will call RF part; 2)
transmitting radio frequency control and amplifying reflected signal part which we
will call electric part; and 3) data collection, data processing, and visualization part
which we will call post-processing part. A transmitting radio frequency control and
an amplifying reflected signal part are based on a research performed at a lecture
and labs designed by researchers at Massachusetts Institute of Technology (MIT)
Lincoln Lab, Charvat et al. (2012) and another lecture and labs designed by a
professor at University of California at Davis, Liu (2013). The radar system
designed at University of California at Davis is based on the system designed at
MIT Lincoln Lab that proposed a design of a small, low cost, and low power
consuming radar. The low power radar proposed by MIT Lincoln Lab is suitable to
operate in any public places without any restrictions for human health because of it
low power transmission, however surveillance area is relatively short and limited. To
expand monitoring area with this proposed low power radar system, the transmit
power of the radar system proposed in this study is enhanced comparing to the
radar proposed by MIT Lincoln Lab. Additionally, the radar system is designed and
fabricated on printed circuit boards (PCBs) to make the system compact and easy
to access for use of various purposed of research fields. For instance, the radar
system can be utilized for mapping, localization, or imaging.

The first part of post-processing is data collection. The raw data received
and amplified through the electric part in the hardware is collected through a
compact computer, a Raspberry Pi 3, that is directly connected to the radar. The
data collected every second and the collected data is transferred to the
post-processing devices, which is a laptop computer in this research. The
post-processing device processes data to estimate range of the object, applies filters
for tracking, and visualizes the results. In the study, a variant of the Advanced
Message Queuing Protocol (AMQP) called RabbitMQ, also called as RMQ
(Richardson, 2012; Videla & Williams, 2012) is utilized for real-time data transfer between the Raspberry Pi 3 and a post-processing device. Because each of the data
collection, post-processing scripts, and visualization processing have to be
performed continuously and sequentially, the RMQ has been used for data exchange
between the processes to assist parallel data collection and processing. The
processed data show an estimated distance of the object from the radar system in
real-time, so that the system can support to monitor a certain area in a remote
place if the two distant places are connected through a network.

This proposed radar system performed successfully to detect and track an
object that was in the sight of the radar. Although further study to improve the
system is required, the system will be highly suitable and applicable for research
areas requiring sensors for exploration, monitoring, or surveillance because of its
accessibility and flexibility. Users who will adopt this radar system for research
purposes can develop their own applications that match their research environment
for example to support robots for obstacle avoidance or localization and mapping.